The use of monocrystalline materials has enabled the passive alignment of optical devices to optical fiber for optical communication with great precision. The use of these materials to replace the requirements for active device optical alignment enables a low-cost, large production capability for fiber optics that have application in the fiber to the home (FTTH) and fiber to the office (FTTO) markets. Accordingly, in the recent past, there has been a great deal of activity and interest in the development of passive alignment of optical devices to optical fibers based on the use of monocrystalline materials. A common material for such use is monocrystalline silicon, as its crystalline properties are well known in the art. In U.S. Pat. No. 4,210,923 to North, et al., as well as other publications on anisotropic etching of silicon for passive alignment teach the preferred techniques for using silicon as an optical bench. (See for example silicon optoelectronic platforms disclosed in "Optoelectronic Integration: Physics, Technology and Applications", 1994 by Kluwer Academic Publishers, pages 399-417 and IEEE Transactions on Electronic Devices, ED-25,(10) 1178(1978), by E. Bassous, the disclosures of which are specifically incorporated herein by reference.
One of the preferred categories of devices in optical communications is the surface emitting and receiving device. To this end, the use of such devices as a vertical cavity surface emitting laser (VCSEL) as well as surface emitting light emitting diodes (SLED) and photodetectors, to include PIN photodiodes, that have a photosensitive surface to receive or emit light from a top or bottom surface has required a great deal of modification to effect the alignment of the device to an optical fiber. In general, to effect the alignment between the device and the fiber using a silicon optical bench, it is required to have the device on a different plane other than that of the fiber, with the light being communicated there between a brightly reflective surface. Examples of such techniques are found, for example, in U.S. Pat. Nos. 5,073,003 and 4,904,036, to Clark and Blonder, respectively, the disclosures of which are specifically incorporated herein by reference. While such technology has its merits in allowing passive alignment to be effected, it is required none the less that the device be actively aligned into position so that the light is properly reflected by the reflective surface. Furthermore, the use of the reflective surface decreases coupling efficiency, since there is an intrinsic loss incurred at each optical surface through dispersive effects. Accordingly, a more efficient system would allow for in line coupling between the optical fiber and the surface emitting/detecting device.
One such example of co-linear coupling of an optoelectronic device to an optical fiber is as disclosed in U.S. Pat. No. 5,179,609 to Blonder, et al. The disclosure of this patent is specifically incorporated herein by reference. This reference to Blonder, et al., makes use of two pieces of monocrystalline material as mounting members that have etched therein detents in complimentary locations on each of the pieces of the mounting members. These detents receive microspheres to effect the alignment of the mounting members to effect the coupling of the device to the fiber. While the reference to Blonder, et al., does disclose the use of other types of alignment fiducials, the complexity of this design, including the alignment microspheres make it impractical for large scale manufacture. Another area of great interest is the miniaturization of transceivers, to include "mini MT" transceiver. This reduced footprint device has the promise for high speed data transmission and reception in the miniaturized package. The industry standard for this structure requires the use of a connector body supporting pins with the pins used to align the optical fiber to the optoelectronic device with lenses for optical coupling disposed there between. These lenses are used to effect the coupling to and from the light detecting and receiving devices, respectively and reduce to an acceptable level any cross-talk to an acceptable level. Further details can be found in the above referenced patent application.
One of the potential drawbacks to the alignment frame for mounting the optoelectronic devices and coupling them to optical fibers as is disclosed in the reference to Jiang U.S. Pat. No. 5,913,002 specifically shown at 202 in FIG. 1 of the application, is in the large scale manufacturability in a precise manner of the frame. To this end, the holes for the guide pins, 205 in the application, for receiving the guide pins, 201 in the application, must be located with great precision. Therefore, what is needed is a technique which enables the precise alignment of the guide pins in the passive alignment frame for the optoelectronic devices in a manner which is both reliable from the standpoint of precision and readily manufactured in large scale to effect a reduced cost in the overall device.